The Hubble Space Telescope didn’t rest during its recent 30th anniversary celebration. Instead, it watched the comet C/2019 Y4 (ATLAS) fragment into at least 30 pieces.
Last December, the Asteroid Terrestrial-impact Last Alert System discovered this comet, and astronomers soon realised it could put on a show the likes of which hadn’t been seen in decades. It would be the brightest comet since Hale-Bopp in 1997. But the comet started to break up into pieces as it approached Earth, so we’ll have to settle for enjoying these Hubble images instead.
Astronomers calculated C/2019 Y4 to have an orbit that lasts 6,000 years. Had it not broken up, it would have been visible to the naked eye just about now. But during March, it brightened far quicker than scientists expected as it travelled closer to the Sun, releasing volatile elements with low boiling points as it heated. On April 6, astronomers detected evidence that the comet had suddenly stopped producing dust, and another team confirmed that it had broken into multiple pieces by April 11 and 12.
We couldn’t see these dramatic events, but Hubble could. Two teams of astronomers, one led by David Jewitt from UCLA and the other by Quanzhi Ye from the University of Maryland, managed to capture the breakup in Hubble images taken on April 20 and 23.
Astronomers aren’t completely sure what causes these fragmentation events. Perhaps it’s due to the force of the emitted gases causing the comet’s nucleus to spin and break itself apart. Jewitt said that further analysis of the data could possibly confirm or rule out whether this off-gassing is what caused the comet to break up, according to a Hubble press release. The images are in incredibly high resolution, capturing fragments down to the size of a house.
The comet is presently passing Mars and will get closest to Earth on May 23. It stinks that we won’t get the incredible show we were hoping for, but perhaps we’ll still get some cool telescope images as a consolation prize.